Embedded-type Cu Nanoparticle with Largely Enhanced Catalytic Activity and Stability Towards Methanol Steam Reforming

Abstract

Hydrogen production through low temperature methanol steam reforming (MSR) reaction plays a critical role in the development of new energy, but remains a great challenge. Herein, we report a Cu/Zn(Ga)Ox catalyst, which is prepared via an interface reconstruction strategy. Interestingly, this catalyst is featured with a unique mortise-and-tenon structure: Cu nanoparticles are embedded into the Zn(Ga)Ox substrate, which ensures a stable Zn-O-Cu+-Ov-Gaδ+ interface structure. The resulting Cu/Zn(Ga)Ox catalyst exhibits 99.3% CH3OH conversion with a H2 production rate of 124.6 μmol gcat-1 s-1 at 225 °C, which is preponderant to the state-of-the-art catalysts. Furthermore, an ultra-high catalytic stability was demonstrated through a 400 h stream-on-line test without obvious decline. Kinetic isotope analysis, in situ spectroscopy characterizations and theoretical calculations reveal that the MSR reaction over Cu/Zn(Ga)Ox catalyst follows formaldehyde oxidation route. The CH3O* and H2O molecule adsorb at adjacent Cu+-Ov interface (intrinsic active site) with oxygen-terminal adsorption configuration, which promotes electron transfer from d-band center of Cu to O (s,p)-band of substrate molecule. This significantly reduces the energy barrier of C−H bond cleavage in CH3O* dehydrogenation (the rate-determining step) and H2O dissociation, accounting for the extraordinarily enhanced H2 production.